Key arrangement



E. BAHR KEY ARRANGEMENT Filed May 13, 1938 March 26, 1940.

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vvvvvvv I Patented 26 194% I v I r I UNITED STATES PATENT OFFICE 2,195,294 KEY ARRANGEMENT Ernst Biihr, Berlin-Charlottenburr, Germany,

assignor to Siemens and Halske, Aktiengesellschait, Berlin-Siemensstadt, Germany, a corporatlon of Germany Application May 13, 1938, Serial No. 207,686

In Germany May 13, 1937 4 Claims. (Cl. 178-456) This application concerns a new and improved is keyed to pass-current of bn0.2 Neper and the signalling system. In describing the invention damping when the circuit is keyed to block curreference will be made to the attached drawrent from passing bs i'Neper, that the four-pole ings wherein: permits passage of alternating current from the Fi ures 1 and 3 to 8 inclusive illustrate varsource l3 at a low resistance of the detectors l ons modifications of my novel and improved and 2 in the series branches and high resistance means for relaying and forming wave energy to of the detectors 3, t in the parallel branch but impose thereon signal characteristics. Each of blocks the' alte at Cu W t e resisthe circuits illustrated includes two or more tellee the series detectors ..2 is h a t pairs of rectifiers or other non-linear devices con- 0f t pa l l d cto 4 s I W- l m nected in balanced or symmetrical circuits with s known arrangement has t disadvanmeans for impressing the wave energy to be modtage that when the control current from source ulated on,the circuit and formed wave energy 5 n Currents pp in the receiving from the circuit. In Figure 1 the balanced keyer l y 0 nn d to the ou in line t or modulator has two non-linear devices in seva u f sai urr ts lyin approx mately n the ries, and a second pair of non-linear devices are Center between the currents appearing at P connected in shunt to the balanced circuit. Fig- S n a d at bl cking Is of the key r eure 2 is a graph representing the o e ati of ment as illustrated in Figure 2. When I 0 inmy new and improved keying s h In Figcludes a receiving relay, current will be supplied ure 3 the series non-linear devices are replaced t r Of a Value Of the Order q d to P- by groups of ch d i hil 'i Figure 4 t crate the receiver. Therefore, the position of the 2 two shunt devices are replaced by several such u e 0f the receiving relay is o er u devi s, h circuits of Figures 5 and are equivocally established. In case of fluctuations modifications of Figure l and in Figures 5 and 6 0f the residuelydamping 0f e line 1 the armathe shunt non-linear devices are connected difture of the receivi g e y W t us move to ferently than in Figure 1. In Figure 7 a bridge and no and give the T E pre si n at the 25 ircuit comprising m including nonqinear receiving station of the character of telegraphic vices replace the parallel or shunting non-linear signals 0 e devices of Figure 1 while in Figure 8 a bridge The shutting off of e cu ent source 5 is circuit similar to the one in Figure 7' replaces ordinarily d in t e telegraph o flc s f longer the series non-linear devices. Modified forms of intervals between the transmitting 01 es es so coupling transformers are used in Figures 7 Such as for instance at nightnd 8, My invention relates to an arrangement by Anegwerk for keying alternating current which the aforementioned disadvantageis eliin-.

prises a transformer 22 having t primary windinated and whereby in the condition of substaning 4 connected t Source of wave energy 3 tially zero control potential, the damping (ho to be keyed and its secondary winding l9 cou- Neper) 0f t e ey arrangement deviates 3 t0 pied to an output line '1 by other means such as Such a Slight ee f the damping t Desa transformer 3|. The line 1 may be coupled Sage (be) or damping at blocking e) that in 40 t any l d r t d t m; A resistance 5 the presence of this slight variation in the dampmay be included in the supply circuit if necesmg of the line, the receiving relay remains n an sary to keep the current substantially constant. unequivocal positieh- Points on the windings l9 and 3| are connected This is achieved in accordance With e inwith any source of keying potentials oreurrent vention making the resistances of the series such as, for example, comprised by source 5, keys branch detectors l and 2 and parallel branch 6 and 9. Two pairs of detectors (non-linear dedetectors 3 and 4 greatly d e ent from each vices) I, 2 and 3. 4 in series are inserted in the other- It is advisable so to choose e alue of series branches and parallel branch respective the hull-damping that be is Outside the a ge 3 1y of the balanced circuit The biasing poten- Neper bolibp. At these values of b0 even In tial of said detectors can be varied in its directhe Presence of Variations of t e level such as 50 tion by means of a key 6 connected to the source appear rdinarily d ring telegraphi transmisof direct current or alternating current 5. The sions, t e r ce ay e a s att acted or redamping. of the network between the poles a, b, leased at the null value of the control potential, 0, and d varies within such wide limits, as for without the relay. being permitted to fluctuate instance between a damping when the circuit beween these two values.

Various ways are possible in obtaining the difference between the resistance values of the rectifiers inserted in the series branch and parallel branch, more especially of the dry-contact rectii'iers. Thus, in the series branch several detectors in parallel may replace the single detectors i and 2 as shown in Figure 3 or in the parallel branch several detectors may be placed in series as shown in Figure 4 or vice versa, or there is employed a combination of these two arrangements. The circuits of Figures 3 and iam otherwise similar to these of Figure .1 with keying means connected at points 40.

It will be especially suitable to connect the detectors in the series branch and parallel branch to the input transformer of the key circuit across different reduction ratios. The reducti'on ratio thereby has the effect that as regards the total damping of the network the resistances in the series branch and parallel branch vary in accordancewith the square of the ratio between the windings. Therefore, the b value comes very close either to the damping value at passage or to the damping value at block-v ins.

If the control potentials are derived in the two directions in the ordinary manner from the same direct current source, it will, furthermore, be advisable by providing resistances in series or parallel to the current source and tapped at different places, to apply the control potential at such a value to the different detector combinations in the series branch and parallel branch, that for each individual detector the control potential has a favorable value, this value depending on the characteristic of the detector. Such arrangements have been shown in Figure 5. In Figure 5 resistances 23, 24 and 25 are connected between the adjacent terminals of the non-linear devices 3 and 4 and the pointat which the keying circuit is connected to the primary 3| which in this case is split into two portions separated by a blocking condenser. The detectors 3 and 4 shunt a portion only of secondary winding ll.

In place ofthe series or parallel connection of detectors in the series branch or parallel branch there may also be employed a bridge circuit of the type of the so-called Graetz circuit in which the control potential is in one diagonal, and the voltage to be controlled in the other diagonal. In Figure '7 the parallel detectors 3 and 4 have been replaced by a bridge arrangement comprising detectors 21, 28, 29 and 30. In Figure 8 the series detectors i and 2 have been replaced by the said bridge circuit which is in one side only of the line. In both of these modifications a transformer having two windings l9 and I9" with different transformer ratios are used. This arrangement has the advantage that though a multiplicity of detectors is present, these detectors have as regards carrier frequency the effect of a single detector.

With the arrangement according to the invention, on complete shutting off of the control voltage sources telegraphic signals heretofore carried by current variations, are no longer simulated. The arrangement according to the invention can moreover also be readily used for single current operation, especially when the single transmission key is connected to the center of the control voltage source. By resorting to particular circuits alternating current telegraphy has been operated heretofore with single current polarized transmission relays. These known arrangements had the following disadvantages. It was necessary to provide a compensation winding and a special compensation current whose value had to be accurately adjusted. Different response periods were encountered at turning of the relay armature out of the null position, furthermore the relay kicked back, i. e., the armature was lifted again although contact was already made. The switching period was greater and varied within wide limits. At a high and brief load as well as at a unilateral load of longer duration, the mechanical and magnetic neutral position of the relay disappeared, so that the relay was after a certain time no longer neutral and finally the telegraphic speed was limited in the case of contact relays owing to the inertia of the mass. These drawbacks resulted in detrimental distortions of the telegraphic signals.

The above disadvantages are overcome by the transmission key circuit according to this invention. Additional distortions are eliminated and furthermore the transmitter key circuit can also be operated with single current in the same advantageous manner and without modifications being necessary. More especially, the telegraphic speed is not limited in the key circuit according to the invention since this arrangementoperates without inertia.

The operation of my invention will now be explained in greater detail with reference to several examples of construction. In Figure 1 two detectors i, 2 and 3, 4 are placed respectively in the series branch and in the parallel branch. In accordance with the position of the transmitter key 8 either the detectors in the series branch or those in the parallel branch permit passage of current. Therefore, currents In and Is appear at the receiving relay whereby the current (In) in the direction of passage is much greater than.

that (Is) in the direction of blocking. The response amperage and release amperage of the receiving relay are approximately the half amperage of In, as shown by the straight line II in Figure 2. In Figure 2 the abscissa represents the time (t) and the duration of a pause between two telegraphic signals (ta-t1) is shown below the abscissa.

' Now, if for instance during the night the control voltage source I is shut ofl at the ofilce in that the switch 9 for instance is opened, the detectors i and 2 in the series branch and detectors '3 and 4 in the parallel branch have the same resistance. Therefore, the current in the network will pass with one half across the parallel circuit and with the other half across the series circuit. Since the total current, and this is also assumed for all following examples, is to be maintained practically constant in that the resistor I! placed in series to the alternating current source l3 and primary winding l4 of the input transformer is chosen about 100 times larger than the resistance of the network inclusive the load of theoutgoing line I of the order of about 100 ohm, the current I; of the generator flowing 1 the current appearing at the receiver is at interruption through the switch 9 one half of the current In in the direction of passage.

- This amperage is shown in Figure 2 by the straight line it which in the present case conforms to the response amperage and release amperage of the receiving relay. Figure 2 readily indicates that in case of variations in the dampin: of the line and variations of the current I caused thereby, the current It easily exceeds or lags behind the response limit and release limit.

ll of the relay in the one or the other direction, sothat the receiving relay begins to vibrate and simulates reception of telegraphic signals. The invention provides means whereby the amperage in the receiving relay can be displaced at zero control potential towards higher or lower values in such a manner that it lies sufliciently far apart from theresponse limit and release limit of the receiving relay such as for instance in the position II or I8. I

Figure 3 shows an example of an arrangement according to the invention. Herein, the detectors l and 2 in the series branch are replaced by four detectors of the same size as that of the detectors 3 and 4 and placed in parallel. Consequently, at zero control potential only /5 of the current fiows in the parallel branch, but A, pass through the series branch so that the receiving relay it receives a current that is 80% of the current In and this current being far away from the release limit of the relay.

In a similar manner Figure 4 shows in the parallel branch several detectors for instance three detectors placed in series. Therefore, if the control potential is zero, the current I= 01' In as indicated by the straight line IS in Figure 2. This amperage is sufiiciently far below the response limit of the receiving .reiay so that at the current 10 the position of the armature 'oi the receiving relay is the same as at the blocking current Is.

In order to enhance the actions attained with the arrangements according to Figures 3 and 4 also both circuits can be combined and detectors in parallel can be employed in the series branch and detectors in series can be inserted in the parallel branch. Vice versa, detectors placed'in series may be inserted in the series branch and detectors placed in parallel may be inserted in the parallel branch.

In order to operate with a smaller number of non-linear means than that required for the series connection and parallel connection of several detectors, it is advisable to use an arrangementaccording to Figure 5, in which the parallel and series detectors are coupled at a difierent ratio with the primary winding of the transformer 22. The particular advantage oi different reduction ratios'resides in that the resistance 01- the detectors varies as regards current distribution with the square of the transmission ratio. The arrangement according to Figure 5 corresponds as regards action approximately to those of Figures 3 or 4- whiie the arrangement of Figure 6 reveals the-contrary conditions of the damping. In the arrangement of Figure 5, resistors 23, 24, 25 are inserted in the control circuit. They are so dimensioned that all detectors have linearity while the control current which renders the detectors of the one direction pervious increases the negative blocking potential for the other detector pair due to the voltage drop of the said control current at the resistors 25 and 23 and 24. The condenser 2' serves for bridging the resistors 23 and 24 as regards alternating current.-

Figure '7 shows a transmitter keying circuit in which the detectors in the parallel branch designated by I, 4 are replaced by four detectors 21, 2,8, 29, 30 in bridge connection. The resistance of the combination consisting of these four detectors is, as regards the carrier frequency, equal to the resistance of a single detector, this being true forthe controlling current as well as for the controlled current applied to and derived from the diagonal points. The shunt action of this parallel detector is still further increased in the arrangement of Figure 7 in that the current to be controlled is passed to the primary side of the input transformer across a special'winding I8 whose reduction ratio is 1:10, while the series detectorsare placed at a third winding IQ of the input transformer whose transmission ratio is 1:2. The transmission ratio of the output transformer Si is 2:1. The resistors 32, 33, 34, 35 and 36 are again so dimensioned that the direct control potential has the same value at each individual detector.

Finally, Figure 8 shows an arrangement in which the Graetz or bridge connection is in the series circuit and not in the parallel circuit.

I claim:

1. In a keying system, a wave energy source, a utilization circuit including a device responsive to wave energy which varies about a selected amplitude, rectifier means in a series circuit coupling said source of wave energy to said utilization circuit, rectifier means efiectivelyin shunt to said series circuit, a control circuit including a variable source oipotential and means for varying said potential connected in shunt to said series and shunt rectifier means. to bias the same to pass wave energy to said utilization circuit of an amrectifier means varies and means for preventing wave energy from said source of an amplitude of the order of said selected amplitude from being impressed on said utilization circuit in the nonkeying condition of said control circuit comprising means connected with one 01' said rectifier means to change the resistance of the circuit including the said rectifier means to thereby alter the amplitude of the wave energy passed by said one rectifier means and consequently the wave amplitude of the wave energy passed from said source to said utilization circuit so that it difi'ers from said selected amplitude by a substantial amount.

2. A system as recited in claim 1 wherein said last named means comprises additional rectifiers in shunt with one of said rectifier means.

3. A system as recited in claim 1 wherein said last named means comprises additional rectifier means inserted in series with said eflective shunt circuit to raise its impedance.

4. A system as recited in claim 1 wherein said series circuit to lower its impedance.

' ERNST BAHR. 

